Newly discovered 3.66-million-year-old footprints in Tanzania reveal that humans' predecessors likely lived in groups of females who shared a common "husband," New Scientist reports. The newfound footprints, among the oldest known, belong to two Australopithecus afarensis, the same species as the famous hominin Lucy, and were found near three other sets of footprints that were originally discovered in 1976.
Of the newly discovered footprints, most belong to a large individual referred to as "S1." The other prints, belonging to "S2," indicate a smaller australopith. S1 was apparently walking in the same direction, at the same speed, and likely the same time as the sets of prints belonging to the australopiths that were discovered in the '70s.
"It has been all too tempting to interpret the original trackways — often reconstructed as belonging to two adults and one juvenile — as evidence of a prehistoric 'nuclear family,'" New Scientist writes. But with the discovery of S1, researchers were left "without words," said Marco Cherin, a scientist at the University of Perugia, Italy.
"They were probably similar in certain respects to those of our cousins, the gorillas, with a single dominant big male accompanied by his females and their offspring," said Giorgio Manzi, another researcher working on the excavations. Using additional data from a 2011 study, the researchers now think that female australopiths would leave their families to join new social groups, making them different from modern gorillas where the males are the ones to leave their families to form new groups.